The antibody drug conjugate, T-DM1, when used alone or in combination with pertuzumab, did not significantly improve overall survival (OS) compared with trastuzumab and a taxane (HT), according to final data from the phase 3 MARIANNE study (ClinicalTrials.gov Identifier: NCT01120184) presented at the 2017 American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago.1

Women enrolled in the study had centrally assessed HER2+ progressive/recurrent locally advanced breast cancer or untreated metastatic breast cancer (MBC) with at least a 6-month interval since treatment with a taxane or a vinca alkaloid.

MARIANNE had shown that T-DM1 alone or in combination with pertuzumab does not improve progression-free survival (PFS) compared with HT in this setting.

The present OS analysis of MARIANNE shows a similar trend to the PFS data. At the cut-off date of May 2016, after a median follow up of 54 months, median OS was 50.9, 53.7, and 51.8 months for HT (365 patients), T-DM1 (367 patients), and T-BM1 plus pertuzumab (363 patients), respectively. Comparisons of the T-DM1 arms with HT were not significant.

Similar observations were noted when patients who received T-DM1 and/or pertuzumab after progressing on HT were censored from the analysis. Dr Barrios noted that there was no subgroup of patients in whom OS was significant in any of the T-DM1 arms.

Grade 3 to 5 adverse events (AEs) were seen less frequently among patients who received T-DM1. Grade 3 to 5 neutropenia was highest in patients on HT (19.3% vs 4.4% for T-DM1 vs 3.8% for T-DM1 + pertuzumab).

While the median OS was similar across treatment arms, a median OS of 53.7 months and fewer grade 3 or worse AEs (vs other arms) supports T-DM1 as an effective and alternative first-line treatment for HER2-positive patients with MBC, Dr Barrios concluded.

Read more of Cancer Therapy Advisor‘s coverage of the 2017 American Society of Clinical Oncology (ASCO) Annual Meeting by visiting the conference page.

Want to read more?

CancerTherapyAdvisor.com is a free online resource that offers oncology healthcare professionals a comprehensive knowledge base of practical oncology information and clinical tools to assist in making the right decisions for their patients.

Our mission is to provide practice-focused clinical and drug information that is reflective of current and emerging principles of care that will help to inform oncology decisions.